‘It’s not a dead zone’: Burns Bog fire one year later

The evening sun fell on the trees at the edge of Burns Bog, playing against charred bark and ghostly wood. Green leaves and growing stems entwined themselves around the dead roots, and rustled in the light breeze.

The noise of Highway 17 melded with the twitter of birdsong and the throaty croak of frogs in a ditch along the edge of the bog. In the distance, a black-tailed deer nosed among the undergrowth.

A year ago to the day, on July 3, 2016, a fire broke out at the base of one of the Corus Entertainment radio towers. Igniting the living layer of peat, it spread across the moss-covered bog and flamed up into the hemlock and pine trees at the edge of the highway. There, it threatened the Tilbury area, prompting an evacuation of industrial properties on Progress Way.

For more than a week, fire crews from Delta, Surrey, New Westminster, Richmond, Metro Vancouver, the B.C. Wildfire Service and even as far away as Hope and Squamish battled the blaze, pulling water from the Fraser River to douse the flames. Winds whipped the fire to a frenzy, and rain helped beat them down. Boat traffic was stopped along the river. Highway 17 was closed between the Nordel connector and Highway 99.

By July 11, the Corporation of Delta reported the fire had been fully contained and there were no new areas of concern. But what had once been filled with salal bushes, Labrador tea, bog blueberry and sphagnum moss was now a blackened wasteland.

Fires in the bog

But, according to Delta’s climate action and environment manager Mike Brotherston, that’s not the case anymore.

“Its very difficult to have a real natural fire in that you’re trying to protect the surrounding areas,” he said. “You need to manage the risks [around the bog]. So then your fire doesn’t necessarily behave the same as it would in a fully natural, uncontrolled setting.”

Burns Bog is encircled by development and the conservancy area is bordered on all sides by highways.

“Because it’s in a relatively limited geographical area, there’s getting to be less of the pristine bog that hasn’t been impacted by fire or peat mining,” Brotherston said. “So we don’t want to lose those areas.”

“Obviously the first priority is to get the fire under control and protect property and life,” he continued, “so we need to use whatever tools — in this case, some fire retardant and water bombers from the river.

“But as things get under control and you have a bit more time to be selective of the water sources,” he added.

Bog water is naturally acidic, low in oxygen and low in nutrients. The fire management plan, which was put in place after the 2005 fire, identifies a number of sites within the bog that can be used to fight fires internally.

These include bog ponds and the neighbouring cranberry fields, which contain water with similar chemical composition to the bog.

But there’s only so much that can be done while fighting the fire to preserve the bog. The rest is a waiting game to see how the already damaged wetland will respond.

One year later: water

At the end of July 2016, Delta hydrologist Sarah Howie went in the bog looking for water.

It’s not terribly hard to find. Water is perhaps the single most important indicator of bog health and, in pristine bogs, is only around 40 centimetres below the surface of the sphagnum moss that covers the ground. In damaged areas, like Burns Bog, the water table is often much lower.

Immediately following the 2016 fire, and continuing on one year later, the water in that area actually raised to 50 centimetres below the surface.

This effect, known as “watering up” in the bog science community, happens when a bog loses its tree cover. No longer being taken up by the roots and expelled by tree leaves, the water stays in the bog and fills the spongy peat.

The Corporation of Delta has been attempting to raise the water level of the bog since it jointly purchased the area in 2004, constructing dams and weirs to mitigate the human-caused drainage and restore the bog to its natural state.

But, she added, “in terms of the long term, [the restoration] actually depends on whether the trees come back or not.”

Trees coming back into the bog depends in part on the composition of the water. Naturally acidic, and low in oxygen and nutrients, most trees can only grow to a dwarf size in a healthy bog.

In a fire-damaged bog, burnt organic materials drift back down into peat and increase the nutrient level in the water. Fire retardant, designed to promote regrowth after forest fires, can also have an effect. Fire retardant was used liberally during the 2005 fire.

“Now those 2005 fire sites are really covered in dense tree cover,” said Robyn Worcester, registered biologist at Metro Vancouver. “What we don’t want to see in the 2016 fire site is for it to become covered in trees again really fast. And especially birch trees, because the birch that is invading the bog isn’t native.”

In the months following the fire, the water had higher levels of calcium and was more acidic.

Of course water chemistry does vary in the bog throughout the year; in summer, when the lack of rain concentrates the minerals in the bog water, it’s common for water to become more acidic and contain larger amounts of calcium, sodium and magnesium — similar to the what could be the effects of a fire.

“So we can’t really say whether that spike was actually caused by the fire or if it was a spike because it was summertime,” Howie said.

The best way to find out would be to do another test at the end of July, and compare the data. Delta is considering do that monitoring this year.

What’s important, however, is that the bog water had returned to normal by February 2017. Regardless of how the spike occurred, the water was back to an ideal state for sphagnum moss growth — the living tissue of a healthy bog.

One year later: vegetation and wildlife

Walking over the site after the 2016 fire, it wouldn’t have seemed like an ideal spot for anything to grow.

“There was just a charred wasteland of charred trees and charred soil,” said the bog’s vegetation specialist, Robyn Worcester.

Although smaller and not as intense as the 2005 fire, it was still “disruptive and damaging,” she said. “You still lost the living layer over most of it, which is the important part.”

That living layer was sphagnum, a bog-specific moss that thrives in nutrient-poor, acidic waters. Growing slowly, it colonizes bogs by releasing spores that travel a few centimetres above the surface.

The moss can hold up to 20 times its own weight in water, allowing bogs to stretch into drier areas. Upon dying, it creates the decomposing plant base that forms the bog’s peat.

At the 2016 burn site, Worcester did find pockets where the sphagnum mosses had survived the fire. And those colonies have already started growing.

“New colonies have established, which is good,” she said. “Although the sphagnum hasn’t gown back as fast as we like, there is some positive in that it does kind of establish on its own.”

Sphagnum, because of its slow growth, wasn’t the first life to move back into the area. That would have been bracken fern, a known colonizer of open fields. Soon after came spiders. Then, dragonflies, bumblebees and birds. Deer and coyotes returned to their habitual spots almost immediately.

“There was definitely a slow period after the fire, but this spring there’s lots going on,” she added. “It’s not a dead zone. It’s full of life.”

The future

Although the vegetation, wildlife and water look promising for now, there’s still lots that needs to be monitored. Perhaps more than monitored.

“With invasive species and restoration, prevention is way better than studying it and trying to figure it out later,” Worcester said. “So we might have to just take action in some cases and just prevent the establishment of birch rather than study it. Because it has been studied at other site.”

In the 2005 fire site, active monitoring didn’t take place until 2010. By that time, birch trees had colonized the area, lowering the water table and shading the sphagnum moss.

UBC masters student Angela Danyluk studied the birch population on that site, and experimented on how removing the trees could improve the bog area. It did increase the water levels, but the birch grew back.

“Part of having the monitoring set up is so we can keep an eye on how things progress,” Worcester said. “But it’s really good that we have the 2005 site as a scenario that we can predicts what’s going to happen. If we start seeing that same pattern then maybe we can get on it quicker.”

Of course, the 2016 site presents more questions than Worcester and Howie can answer. And it will likely present new and unforeseen problems as it continues to recover after the fire.

But, Worcester said, it has potential to become a more pristine bog.

“There’s really nice parts of it on the edge of the burn that if the sphagnum can be reestablished, it will be boggy,” she said.

“And maybe if the trees dying has helped increase the water table and the sphagnum can get established, then yeah, maybe it could be more boggy. That would be a best case scenario for sure.”